A Chinese team has recently made key advances in the study of high-voltage electrolyte systems that are expected to allow lithium-ion batteries to achieve higher energy densities.

Researcher Wu Jianfei's team at the Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences, has developed a new high-voltage fluorinated electrolyte system that increases the operating voltage of the NCM811 cathode material from 4.2V to a breakthrough 4.6V, according to a report in Science and Technology Daily today.

Current lithium-ion batteries have been widely used in electric vehicles due to their excellent electrochemical performance, and cathode materials are one of the key factors affecting the performance of lithium-ion batteries, the report noted.

Using high-energy cathode materials, such as NCM811, and increasing the battery operating voltage above 4.2V are the most effective ways to achieve higher energy densities, according to the report.

However, conventional carbonate-based electrolytes cannot be adapted to high-voltage battery systems, and ternary cathode materials show a lot of side reactions at high voltages, leading to capacity decay.

Wu's team's research significantly increased the capacity and operating voltage of the high nickel ternary cathode system and suppressed the structural phase change of the NCM811 cathode at high voltage, thus improving the energy density and cycling performance of the system, according to the report.

Their research also constructed stable CEI and SEI to achieve reversible and stable cycling of high-load capacity high nickel ternary system batteries at high voltages, the report said.

These studies break through the barrier of high nickel ternary cathode under high voltage within the serious capacity decay, providing new ideas and ways to design high energy density lithium-ion batteries, according to the report.

It is worth noting that the current energy density of lithium-ion batteries is considered to be close to the physical limit, and if the study is applied, it may bring new imagination to the existing lithium battery industry.

In the pursuit of higher energy density, many companies have begun to shift their attention to solid-state batteries, a new technology that is expected to break through the current capacity density bottleneck of liquid lithium-ion batteries, thus bringing longer range for electric vehicles.

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